Method and Apparatus for Packaging a Collective Product, and Such Packaged Product

ABSTRACT

System, hardware, and methods for agitating a package pre-form containing a charge of product elements thus to provide for product settling in the package pre-form before forming the final transverse seal. The product is caused to settle in the package pre-form by apply a plurality of rapid jerk-type acceleration forces to the packaging material, thus to cause rapid longitudinal and/or lateral acceleration in the packaging material.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part (CIP) application of U.S. patentapplication Ser. No. 15/217,494 (attorney docket V01.005-02US),“Settling Product in a Package”, filed Jul. 22, 2016 and currentlypending, which claims priority under 35 U.S.C. 119(e) to U.S.provisional patent application 62/199,785 (attorney docketV01.005-01UP), “Settling Product in a Bag”, filed Jul. 31, 2015 and nowexpired. Each of these applications is fully incorporated herein byreference, except to the extent it or they may be directly contrary tothe present application.

FIELD OF THE INVENTION

This invention relates to the packaging of products, with particularapplication to products that are made up of numerous product elements orpieces that can shift in position, orientation, and placement relativeto each other, and that are not attached to each other, such that acollection of such product elements is susceptible to settling, wherebythe collection of product elements can have different overall volumes,or can rise to different heights in a given bag or package, depending onhow well packed the product elements are relative to each other.Non-limiting examples of such products are dry food products such as aload or serving of popped popcorn, chips (such as potato chips, cornchips, tortilla chips, or pita chips), breakfast cereals, certain petfoods, and the like, but can also include non-food products such as petbedding, and certain types of hardware items, chemicals, and plantseeds. We refer to such a product as a “collective product”. Thecollective product may be homogeneous, whereby the product elements areall or substantially all of the same type or class, e.g., substantiallyall the product elements may be popped popcorn pieces, or they may allbe potato chips, and so forth. Alternatively, the collective product maybe non-homogeneous, whereby some product elements are of a differenttype or class than other product elements, e.g. as in the case of abreakfast cereal that includes both flakes of grain (a first type ofproduct element) and individual nuts or nut pieces (a different secondtype of product element), optionally also including another third typeof product element, etc. The invention relates to methods, machines, andsystems for packaging such collective products in a bag or package thatcomprises a flexible packaging material.

BACKGROUND

Vertical Form Fill and Seal (VFFS) machines have been used for manyyears to package a wide variety of products in bags made with flexiblepackaging material.

In a VFFS machine, product is inserted into flexible packaging materialas the packaging material is being formed into a flexible package, theproduct flowing along a downwardly-directed path, by the force ofgravity into a package pre-form. The process involves:

-   -   drawing flexible packaging material, as a flat sheet, from a        generally continuous roll of such material,    -   advancing the packaging material through a forming shoulder (or        collar) and about an outer surface of an upwardly-oriented        forming tube and thereby partially forming a package, including        making a longitudinal seal in the packaging material where        longitudinally-extending edges of the packaging material overlap        each other, and forming a transverse seal at the bottom of the        partially formed package, thereby making a package pre-form,    -   measuring a predetermined quantity of the product to be        packaged, and advancing the metered quantity of product to a        position overlying the package pre-form,    -   dropping the metered quantity of product down through the        forming tube and into the package pre-form, and    -   subsequently sealing the top of the package pre-form, forming        another transverse seal in a trailing portion of the packaging        material upstream of such top seal to provide a bottom seal for        a next (upstream) package pre-form, and cutting the sealed        package away from such trailing portion of the packaging        material after again advancing the packaging material.

One objective of the packager, who uses VFFS machines, is to meetregulatory requirements that the package state the quantity of productin the package. The quantity of product in the package is typicallyprinted on the package, stating the weight of product contained in thepackage. Thus, it is critical to the packager that the weight of productin the package is always within the tolerances allowed by e.g.government regulation.

In meeting the weight requirements, the packager faces a variety ofchallenges. For example, the raw material used in manufacturing the e.g.food product may vary with time, or may vary when sourced from more thanone supplier. The process used in manufacturing the e.g. food productmay also vary with time, or may vary between different manufacturingfacilities. The packaging material may also vary with time, or may varywhen sourced from more than one supplier.

The challenge for the packager is to provide a quality package, wherethe weight of product in the package consistently meets regulatoryrequirements, where the packages use a consistent quantity/length ofpackaging material for each package unit, while consistently presentingthe consumer with a package which appears to be “full” of the product.

If the package appears to be less than “full”, the consumer perceivesthat he/she has been cheated. If the package is overfull, the packagerexperiences an unacceptably high incidence of leakers which must bediscarded as not meeting quality standards.

Another objective of the packager relates to the cost of the packagingmaterial. It is not uncommon for the cost of the packaging material torepresent a significant fraction of the overall cost of producing thepackaged product. Accordingly, the packager has an incentive to limitthe quantity of packaging material used in fabricating each unit of thepackaged product.

Certain characteristics of the finished product can provide additionalchallenges to the packager. For example, the product may be fragile,and/or the product may be light weight, and/or the product may benon-uniform, product element to product element. Such productcharacteristics are taken into consideration when setting up thepackaging operation.

An example of a non-uniform product, e.g. where product density changesdue to manufacturing variations from one batch, or from one portion of abatch, to another, is popped popcorn. In the process of popping popcorn,the first popped kernels or pieces tend to be relatively light or lessdense because they have little opportunity to absorb popping oil, andthus remain relatively dry and light. However, other popcorn seedsremain in the popping oil for longer periods before popping, and thelonger this time period is, the denser or heavier these later poppedkernels tend to become. Thus, if care is not taken to thoroughly mix thebatch of popped popcorn before packaging, a first charge of popcorn fora first bag may predominantly comprise the relatively lighter, lessdense popcorn pieces, and a second charge of popcorn for a second bagmay predominantly comprise the heavier, more dense popcorn pieces. Thefirst charge will thus occupy a larger volume than the second charge,even though the two charges are the same weight or mass. With apackaging process designed to seal all bags regardless of suchvariability, the second bag will have an excessive amount of air(referred to as head space) in the package. By using a bag lengthdictated by the lower density, higher volume product charge, thepackaging process produces an excessive amount of head space forpackages containing the higher density, lower volume product charges.

Even where the product is not fragile, or not light weight, or notnon-uniform, the product can still arrive in the package pre-form in abulk density which is less than desired. Accordingly, increasing thebulk density of the product in the package, as well as improving theconsistency of the density, package to package, is desirable for thepackager.

The package forming action of a vertical form fill and seal operationstarts by drawing a generally continuous length of flexible packagingmaterial from one or more rolls of e.g. flexible film or flexiblelaminate and advancing the packaging material to typically the top of arigid, typically metal, forming tube, wrapping the packaging materialabout the forming tube, and drawing the packaging material in a downwarddirection along an outer surface of an outside wall of the forming tube,thus to define side walls of the package/bag being produced.

In the process of so transforming the flat roll stock into a tubularconstruct, the flat roll stock is advanced over and about a formingshoulder which is located at the top of the forming tube. As thepackaging material passes over and about the forming shoulder, the flatroll stock is converted to a tubular construct. The forming tube is sosized and configured that, as the packaging material is formed about theforming tube and into the tubular construct, the width of the continuouslength packaging material is overlapped longitudinally onto itself. Alongitudinal seal is subsequently formed by a heated elongate platenpressing the packaging material against the forming tube at thelongitudinal overlap. In the alternative, the longitudinal seal can beformed as what is known as a fin seal.

A transverse seal bar forms a first transverse seal across the width ofthe tubular construct below the forming tube at about the same time,transforming the tubular structure into a longitudinally sealed, tubularconstruct, contiguous with a trailing portion of the roll stock, thetubular construct defining a package pre-form sealed closed at the lowerend thereof and being open at the respective upper end of the tubularconstruct.

Simultaneously with the forming of the first transverse seal at thelower end of the tubular construct, the transverse seal heads also forma second transverse seal immediately adjacent the first transverse seal,at the top of the underlying, and next preceding, tubular construct,thus to close and seal that next preceding tubular construct as a closedand sealed package. The transverse seal apparatus can also make atransverse cut across the width of the tubular construct between thefirst and second transverse seals.

The transverse seal formed at the bottom of the formed tube of packagingmaterial, in combination with the longitudinal seal along the length ofthe tube, provides a partially confined volume as a package pre-form,such that the so-partially-formed tube can receive and contain, andthereby capture and hold, and control the location of, the measuredquantity of product which is subsequently dropped downwardly into thetube.

Once the package has been partially formed by the formation of thelongitudinal seal, and by the formation of the first transverse seal atthe bottom of the partially-formed package, a measured quantity ofproduct is fed to a location over the top of the package, and is droppeddownwardly under the force of gravity into the forming tube, and intothe partially formed, longitudinally sealed tubular package construct.After the predetermined quantity of product has been dropped, or duringsuch drop, the packaging material is again advanced, downwardly belowthe forming tube, as the next following length of packaging material isfed over the forming tube. The next following length of packagingmaterial is sealed longitudinally at the platen and is sealedtransversely below the forming tube. As the transverse seal jaws moveagainst the packaging material to form the lower transverse seal in thenext following length of packaging material, the seal jaws also form thetop, and closing, seal in the underlying package and optionally cut theso closed and sealed underlying package away from the overlying nextfollowing length of packaging material.

The basic concept of the vertical form fill and seal design requiresthat flexible packaging material to be drawn/moved one package/unit eachtime a measured quantity of product is fed/dropped into the top of theforming tube.

Multiple different methods have been used to draw the film about theforming shoulder and down over the forming tube. Early machines hadmovable transversely-extending seal jaws generally mounted to a carriagewhich moved the jaws up and down, as well as moving the seal jawstransversely toward and away from the packaging material in forming thetransverse seals.

Such movement of the transverse seal jaws was typically a sinusoidalmotion whereby the transverse seal jaws moved upwardly to the top of thestroke, below the forming tube, as the jaws transitioned from a closed,sealing configuration, to a generally open configuration. At the top ofthe stroke, the sealing jaws would close on the next length of theflexible packaging material, above the product which had been droppedinto the package pre-form, and thereby flatten the top of the tube whilesealing the top of the underlying filled package and the bottom of theoverlying next second length of packaging material which was still inthe process of being formed into a package, and wherein the longitudinalseal had already been formed.

Heat would be applied to the closed seal jaws so as to seal thepackaging material transversely on itself and to cut away the closed andsealed package/bag as the next second length of the packaging materialwas drawn over and onto the forming tube as the still-closed sealingjaws moved in a downward direction. During the downward pull, a knife,or a heated wire, located between the upper and lower sealing jawssevered the underlying filled package from the overlying tube which wasstill in the process of being formed.

When the sealing jaws had progressed down by a unit package length, thesealing jaws were opened to release the so-sealed and severed underlyingpackage. This automatically stopped the film pull and stopped thetransverse-seal-and-cut operation. At the same time, the product-filledfirst package, which had just been produced and cut away, dropped onto adischarge conveyor or the like, and the next/second overlying length ofpackaging material, already longitudinally sealed, was drawn to aposition where the top of that length of material was below the formingtube.

The platen then made the longitudinal seal on the next/third length ofpackaging material, after which a next second measured quantity ofproduct was dropped into the top of the forming tube thus into thepartially-formed second package, while the now-open transverse seal jawsmoved to the upper extremity of their range of movement where the pullcycle began again, with the transverse seal jaws closing on the top ofthe second length of packaging material, thus flattening the packagingmaterial between the seal jaw surfaces at the top of the second packagebeing formed, with the product trapped between the earlier-formed bottomseal of that second bag, and the now-being-formed top seal.

Speeds in the above-described method were limited by the inertiasinvolved in moving the heavy transverse sealing structure up and down.An additional problem related to the requirement to provide electricalpower to seal jaw heaters, and to provide cable connections totemperature sensors. Because of the constant flexing of the respectiveelectrical connections when moving the seal jaws up and down, theelectrical cables would periodically break, accompanied by correspondingmaintenance and out-of-service costs.

In a subsequent version of VFFS devices, pull belt devices were locatedon each side of the rigid forming tube, alongside the platen, to pullthe packaging material. These devices consisted of two belts, eitherdriven by a single prime mover operating in cooperation with a gearbox,or driven by two individual prime movers, each driving one of the pullbelts. Such devices would run for a programmed period of time topull/draw a desired length of flexible packaging material onto theforming tube, and then stop while the platen engaged the packagingmaterial in forming a longitudinal seal. The significant advantage withthe pull belt system was that the transverse sealing hardware/jaws couldbe fixed vertically in position with respect to the machine frame, thusto move only horizontally. While the open/close motion still had to beaccommodated by the electrical cables, this eliminated the up and downmotion of the jaws of the previous generation of VFFS machines, with arespective reduction in cable failures.

Another version of the pull belt design had the pull belts continuouslyadvancing while incorporating a drive for moving the pull belts intocontact with the flexible packaging material to pull packaging/bagmaterial down along the rigid forming tube, and for moving the pullbelts away from the packaging material when it was not desired to pullpackaging material down along the forming tube.

Pull belts driven by various means were known during this time, but oneof the problems commonly experienced was a difficulty when pullingcertain films (flexible packaging materials), particularly very delicatefilms such as filter paper, or films that had an extremely highcoefficient of friction between the inside surface of the film and theoutside surface of the forming tube. If pulling the film along theforming tube was difficult or impractical as a result of the film'stendency to stick to the tube, in some cases, the pressure of the pullbelts against the tube (with the film sandwiched therebetween) wasincreased so the pull belts would more securely engage the film.However, if the coefficient of friction between the film and the formingtube was greater than the coefficient of friction between the film andthe pull belts, this approach would not work to help move the film. Insuch cases, other techniques were employed to reduce the amount of pullrequired to move the film over the forming shoulder and along theforming tube. One such early technique involved reducing the coefficientof friction between the packaging material (film) and the forming tubeby placing Teflon™ tape, or another slippery or low-friction material,on the outside of the forming tube such that the pull belt would pressagainst, and the film would contact, the low-friction tape or othermaterial rather than the higher friction surface of the original formingtube. Another early technique employed what was referred to as a powerunwind. This typically took the form of a motorized means that waseither placed on the film roll (i.e. on the roll of flexible packagingmaterial), or incorporated in the film unwind mechanism, and was used inconjunction with a film tension detector. In either case, the motorizedmeans would activate or engage to provide tension relief when thedetected film tension was high, and would deactivate or disengage toprovide less or no tension relief when the detected film tension waslower. Machines made by the Hayssen Manufacturing Company used a niproller assembly between the film unwind stand and the forming shoulder.This nip roller assembly, also referred to as a measure roll, served twofunctions: (1) as a power unwind to reduce the pull required by the pullbelts to pull the film over the forming shoulder, and (2) to meter thefilm, such that the bag length could be determined directly by therotation of the measure rolls, and both the bag length and film pullvelocity could be directly controlled by controlling the rotation of themeasure rolls. Reference is made to U.S. Pat. No. 4,288,965 (James),U.S. Pat. No. 4,391,079 (Cherney), U.S. Pat. No. 5,377,474 (Kovacs etal.), U.S. Pat. No. 5,485,712 (Cherney et al.), and U.S. Pat. No.6,131,373 (Chemey).

Thus, in subsequent versions of the pull belt design, a set of measurerollers was added upstream from the pull belts to better control the baglength. Bag length was initially entered in machine degrees in asoftware program or recipe which could be stored for future use. In somesoftware versions, bag length can instead be entered into the controlsystem in terms of millimeters rather than in machine degrees or time.

In this regard, “machine degrees”, sometimes alternatively referred toherein as “pull degrees”, or simply “degrees”, is a machine systemparameter known to those of ordinary skill in the art, and is directlyproportional to time as measured in seconds (or milliseconds, etc.).“Machine degrees” is thus simply an alternative measure of time. Themachine degrees parameter is convenient and helpful in the design andoperation of machine systems because it is standardized or scaled to therepetitive cycle time of the machine, e.g., to the time required for apackaging machine to completely process one bag or package of product,measured e.g. from the start of the cycle for one bag to the start ofthe cycle for the next bag. The multiplicative factor or scaling factorthat relates machine degrees to time in seconds is such that there areexactly 360 machine degrees (beginning at 0 and ending at 359) in onecomplete cycle of the machine process, i.e., in one cycle time. Thus,for example, 36 machine degrees can always be used to representprecisely one-tenth of one complete machine cycle (or cycle time),regardless of how long that machine cycle lasts in terms of seconds, andregardless of how many bags per minute the machine is producing.

In some versions which used the measure rollers, a mechanical gearboxwith a fixed gear ratio was used to drive the measure roller, whichdetermined the bag length, whereby the gearbox controlled the operationof the system.

Stepper or servo motors have been used as prime movers for advancingflexible packaging material (film) in VFFS systems. That is, advancementof the flexible packaging material in such systems has been carried outby stepper or servo motors coupled to pull belts in contact with theflexible packaging material to accomplish the advancement. In suchcases, a “⅓-⅓-⅓” velocity profile was typically used for ease ofcalculation. That is, the total pull time T was divided into three equalparts, where the stepper or servo motor caused the packaging material toaccelerate (starting from a zero velocity) over the course of the first⅓ of the pull time, then advanced the packaging material at asubstantially constant velocity for the next ⅓ of the pull time, andthen decelerated the packaging material over the course of the final ⅓of the pull time, finishing again at a zero velocity. In most cases,such as in the case of a single-pull profile, the total pull time Trefers to the time required to pull the packaging material a lengthequal to the bag length. However, in other cases, such as where the baglength is close to, equal to, or greater than the length of thelongitudinal seal made by the heated platen (e.g. for a two-unit pull),the total pull time may refer to the time required to pull the packagingmaterial a substantial portion, e.g. at least ⅓ or at least ½, but lessthan all, of the bag length, the exact amount depending on designdetails of the bag and of the packaging machine. In any case, a givenfilm pull corresponding to one total pull time T is generally separatedfrom an immediately preceding or an immediately subsequent film pull(which may have the same total pull time T or a different total pulltime, and may have the same pull length or a different pull length,relative to the given film pull) by at least one sealing operation,whether it be a transverse seal, a longitudinal seal, or both atransverse seal and a longitudinal seal. Pull parameters for a ⅓-⅓-⅓exemplary prior art, single-pull profile, can be calculated as follows:The velocity profile is assumed to be the ⅓-⅓-⅓ profile, but can bechanged as required.

If a 250 mm bag is desired with 15 degrees of machine motion at 30packages per minute, the programmed data are as follows:

Bag Length=250 mm

Packages/minute=2 seconds per machine cycle

15 Degrees=15/360 (2000 milliseconds)=83⅓ ms

Command Counts=1000 Counts/Revolution

For this example, the calculation of velocity can be accomplished asfollows:

-   -   a) The distance of 250 millimeters must be made in 83⅓ ms.    -   b) The circumference of the measure roll is 6.38 inches or 162        mm    -   c) The 250 mm pull requires 1.543 revolutions.    -   d) 1.543 revolutions at 1,000 pulses per revolution require 1543        counts.    -   c) Thus, 1543 counts must be produced in 83⅓ ms.    -   f) The velocity profile can be represented as illustrated in the        graph of FIG. 1 which shows velocity over the total pull time,        T.

FIG. 1 represents the actual velocity profile which accelerates from 0velocity to maximum velocity (VMAX) in 83⅓/3 (27.77) ms, runs at VMAXfor 83⅓/3 (27.77) ms, and decelerates from VMAX to 0 in 83⅓/3 (27.77)ms.

The profile of FIG. 1 can be regrouped into a rectangular waveform asillustrated in FIG. 2 with VMAX as the peak velocity, and ⅔ T or0.6667×83⅓ ms=55.6 ms as the time.

Velocity Calculation

VMAX can be determined from the following equation:

Distance=(2×VMAX×T)/3

With Distance=250 mm=1.543 revolutions=1543 counts and T=83% msVMAX=(3×Distance)/(2× T)=4629 counts/166% ms=27.77 counts/ms=27,774counts/sec

Acceleration=VMAX/(T/3)=27774×3/T=999,864 Counts/Sec/Sec

Deceleration=−Acceleration=−999,864 counts/sec/sec  Acceleration andDeceleration Calculations

The above algorithms provide key elements of the pull, the maximumvelocity, and the acceleration and deceleration factors. If noregistration is required, a controller, using the calculated profile,will operate the system satisfactorily, dispensing the desired baglengths. Changing any pull parameter (pull length, pull degrees, ormachine speed) will cause the system to recalculate the parameters andadjust the respective drives accordingly.

The above calculation illustrates the computation for a single pull.Conventionally, a unit package is pulled in one or two pulls dependingon the length of the longitudinal seal. If the package length is longerthan the longitudinal platen seal bar, then two or more pulls are usedfor a given package unit. FIG. 3 illustrates the velocity profile for atwo-pull package. In the figure, the first and second film pulls areshown to be substantially the same, each having the same total pull timeT and the same velocity profile. In the time period 302 (which is not toscale relative to the pull times T, and would typically be longer thanthe pull time T) between the two film pulls, during which the flexiblepackaging material is stationary, a longitudinal sealing operation wouldoccur. Whatever the number of pulls, the longitudinal seal platenengages the overlapped edges of the packaging material to form alongitudinal seal each time the package material velocity reaches zero.In a typical two-unit pull, each pull approximates half of a unitpackage length. The longitudinal back seal is performed at the end ofeach pull, or in some cases at the end of each completed bag length,such that the ends of the respective longitudinal seals overlap eachother, the lengths of the overlapping seals depending on the lengths ofthe packages being formed.

In some applications of VFFS packaging, some of the product, whendropped down through the forming tube, ended up in the sealing area ofthe packaging material after completion of the film pull or pulls.Closing of the seal jaws when product is in the seal area results inproduct being trapped in the attempted seal thus producing what isreferred to in the industry as a leaker. This allowed the product tospill out of the bag, or allowed air to enter what should have been asealed, air-tight package, whereby the resulting package could not passquality control inspection.

One proposed solution to this problem of product ending up in the sealarea was to make the bag longer by using longer lengths of packagingmaterial for each bag, in anticipation that all product would fall pastthe seal area. While lengthening the bag resulted in some reduction inthe number of leakers, packaging material is typically a substantialfactor in the cost of producing a unit of packaged goods, especially inthe case of snack food products. As a result, there is a financialincentive/motivation to limit the cost of packaging material.Accordingly, lengthening the bag is not an acceptable long-term option.

Another proposed solution to the leaker problem is to not use a longerlength of packaging material, but rather to employ a shaker/settlerwhich, for example may be a plate which repeatedly contacts and thusagitates, the partially-formed package, for example agitating a plateagainst the bottom of the package pre-form, after the product is droppedinto the package pre-form. Such agitation against the outside of thepackaging material settles the product in the package before the topseal is formed. In some implementations, such shaking provides enoughsettling of the product in the packaging material, and enough agitationof the product elements that any product elements in the seal area fallaway from the seal area, and thus enable successful sealing of thepackage, sometimes while using a relatively shorter length of thepackaging material.

Some snack food products which are not particularly fragile, such aspopcorn, or more agitation tolerant products, are well suited to use ofa shaker plate to help settle the product in the package in order tolimit the amount of packaging material being used or to effect releaseof product from the seal area. However, using a mechanicalsettler/shaker is a problem for more fragile products such as numerousvarieties of chips, and flake products such as breakfast cereals, whichcan be broken by the use of a machine element mechanically agitatingagainst the outside surface of the packaging material.

Where, in the prior art, a plate or other shaker impacts the outsidesurface of the packaging material in the partially formed package,shaking typically takes place after the pull of packaging material hasbeen completed and the packaging material is not moving, in which casethe shaking adds to the total machine cycle time, and thus results in alower number of packages being produced per minute. In someimplementations, shaking constitutes a machine element tapping theoutside surface of the packaging material on a side of the packagepre-form, in order to encourage settling of the product contained in thepackage pre-form, after the product is deposited into the packagepre-form and during the subsequent downward pull of packaging material.Regardless of the shaking configuration, such shakers/settlers sharesome common drawbacks, as follows:

Most implementations involve shaking the filled bag after the pull iscompleted, which adds to the total machine cycle time resulting in alower through-put of packages per minute.

No matter what mechanism is used to impact the outer surface of thepackaging material, the mechanical shaker/settler requires a drivercoupled to a mechanical system to impart the shaking activity, thusrequiring additional energy to operate the system.

For all known shakers, the mechanical systems can be adjusted to modifythe shaking action being imposed on to the packaging material and theproduct being run. Thus, every time the machine is set up to run adifferent product SKU (stock keeping unit), the machine must be adjustedfor producing that SKU. Such set-up capability adds a significantincrement in initial equipment cost to the machine operator, as well asincreased set-up time for any given product run, and additional machineelements to be maintained and/or repaired.

The somewhat violent nature of the shaking activity results in notinfrequent mechanical failures of the shaking system, which failures areassociated with increased maintenance and repair costs, as well asdowntime costs.

The somewhat violent nature of the shaking activity can cause breakageor deformation of product in the package.

It is therefore desirable to provide an improved packaging system andmethods which provide for product settling while overcoming the aboveproblems.

Accordingly, it is desirable to provide systems and methods which leavethe seal area clear of product without increasing the length ofpackaging material used per package unit.

It is also desirable to provide systems and methods which cause productto settle in the package pre-form before the final transverse closureseal is formed.

It is further desirable to provide such systems and methods wherein theapplication of energy to cause settling of the product is sufficientlygentle that product in the bag is not unacceptably damaged.

It is still further desirable to provide such systems and methodswherein the intensity of the agitation of the packaging material can beadjusted according to the energy input tolerance of the product beingpackaged.

It is yet further desirable to provide such systems and methods whereinthe finished package presents the consumer with an apparently fullpackage while using a consistent length/quantity of packaging materialand limiting the quantity of packaging material used.

One, some, or all of these and other objectives may be achieved by thevarious embodiments illustrated herein for the invention.

SUMMARY

This invention provides vertical form fill and seal (VFFS) machines andsystems, and the like, with a settling feature capable of avoiding anyexternal object impacting the outer surface of the packaging material,and which causes settling of a collective product contained in a packagebeing formed, before the final transverse seal is made to form theclosed and sealed package. The new settling feature can employ the samemechanism that is used to advance or pull the packaging material throughthe VFFS machine, but where that mechanism is controlled or driven in arapid sequence of short, strong accelerations or decelerations or both,to impart a jerking motion or agitation to the tubular package pre-formand its contents, thus promoting settling of the product in suchpre-form. (Agitation of the tubular package pre-form by other means,such as by the use of mechanical vibrating or shaking devices thatcontact the bottom, side, or any outer surface or other surface of thepackage pre-form can thus be eliminated, or, if desired, such othermeans of agitation can be used in combination with the disclosedsettling techniques and systems.) The disclosed settling feature ishighly adjustable, whereby the intensity of the energy transferred tothe packaging material can be adjusted according to how fragile, or not,is the product which is to be packaged. Reduced product damage orbreakage can thus be achieved. For a product such as (popped) popcorn,which has a relatively lower sensitivity to the settling energy input,the input energy intensity can be set relatively higher whereby thelength of time over which the settling energy input is needed, in orderto achieve a particular degree of settling, may be relatively shorter.By contrast, for a product such as potato chips, which have a relativelyhigher sensitivity to the intensity of the settling energy, the energyintensity input can be set relatively lower whereby the product iseffectively caused to settle as desired, without the product beingdamaged by the settling process. However the length of time over whichthe settling energy input is needed in order to achieve a given degreeof settling may be relatively longer for a lower energy intensity inputthan for a higher energy intensity input.

The disclosed methods and systems may be used to produce sealed packagesof a given collective product, where such a sealed package can (a)incorporate less flexible packaging material, e.g., have a shorter baglength, or (b) have a smaller percentage of damaged product, or both (a)and (b), relative to a counterpart or comparable sealed package made bypreviously known methods and systems.

The settling feature is provided by using the VFFS machine controller todrive the drive system (that is to say, to drive the system that pullsthe flexible packaging material through the machine), for example todrive measure rollers, and respective pull belts, at rapidly changingspeeds, whereby the measure rollers and pull belts advance the packagingmaterial in a series of jerks, which can also be referred to as astutter-step drive of the rollers and belts. The collective stutter stepadvance of the measure rollers and pull belts causes the packagingmaterial to advance at a corresponding stutter step motion and rate.

The stutter step advance of the packaging material causes motion both inthe packaging material and within the product contained in the packagingmaterial.

The overall result of the so-imposed motion is that the product elementsin the package-being-formed are set into motion. Product elements whichare loosely attached to the packaging material in the seal area arereleased from such attachment and tend to fall by gravity into the massof the contained product, whereby the seal area is freed from at leastsome, typically all, of the product which would have otherwise stayedattached to the packaging material in the seal area. In addition, thecollective motion of the packaging material and the contained productelements causes the product to settle in the package pre-form such thatthe height of the top of the product is lowered. Such lowering of thetop of the product contents in the package pre-form enables the packagerto limit the quantity of packaging material used to package the product.

Also disclosed are methods of making a sealed package containing acharge of compound product, such a method including: forming a tubularpackage pre-form by steps that include wrapping flexible packagingmaterial around a forming tube, sealing edge portions of the packagingmaterial together to form a longitudinal seal, and sealing otherportions of the packaging material together to form a first transverseend seal; advancing the flexible packaging material along and past theforming tube using a pulling apparatus adapted to engage and pull theflexible packaging material; and loading the charge of compound productinto the tubular package pre-form through the forming tube. The methodalso includes agitating the tubular package pre-form using the pullingapparatus to settle the compound product in the tubular packagepre-form. The agitating step may form a portion of the advancing step,or it may correspond to the entire advancing step. The agitatingpreferably includes advancing the flexible packaging material in aseries of jerks using the pulling apparatus.

The pulling apparatus may advance the flexible packaging material in auni-directional manner, and the pulling apparatus may be or include apull belt. The agitating step may begin before the loading step ends.The agitating step may be carried out over an agitation period and theloading may be carried out over a loading period, and the agitationperiod may at least partially overlap the loading period, for example,in some cases the agitation period may substantially completely overlapthe loading period. Alternatively, the agitation and loading periods maynot overlap at all. Also disclosed are sealed packages made by thedisclosed methods, each such sealed package containing a charge ofcompound product that has been settled using the disclosed techniques.

Also disclosed are vertical form fill and seal (VFFS) machines thatinclude: an unwind station for receiving a roll of flexible packagingmaterial; a forming tube around which the flexible packaging materialcan be wrapped; a pulling apparatus adapted to engage and pull theflexible packaging material along and past the forming tube; one or moreseal stations, disposed proximate the forming tube, at which edgeportions of the flexible packaging material are sealed together to formlongitudinal seals, and other portions of the flexible packagingmaterial are sealed together to form transverse end seals, thereby toform a series of tubular package pre-forms from the flexible packagingmaterial; a drop station from which a charge of compound product can bedropped into a given one of the tubular package pre-forms through theforming tube; and a controller coupled to at least the pullingapparatus, the one or more seal stations, and the drop station, whereinthe controller is configured to agitate the tubular package pre-formusing the pulling apparatus to promote settling of the compound productin the given tubular package pre-form. The pulling apparatus may be orinclude a pull belt, and the controller may be configured to agitate thetubular package pre-form by operating the pull belt according to aseries of short jerks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph representing a typical single-pull prior art velocityprofile.

FIG. 2 is a regrouped, rectangular waveform illustration of the velocityprofile of FIG. 1.

FIG. 3 is a graph representing a typical double-pull prior art velocityprofile.

FIG. 4 is a schematic side elevation view of a packaging system of theinvention, showing a step where product has been dropped into apartially-formed package to form a pre-formed tube.

FIG. 5 is a schematic side elevation view as in FIG. 4 where the topseal is being formed in the product-filled package and the bottom sealis being formed in the next trailing length of packaging material.

FIG. 6 is a schematic side elevation view as in FIGS. 4 and 5 where thefilled and sealed bag has dropped onto a take-away conveyor, and thesystem is ready to fill the next length of packaging material.

FIG. 7 is a schematic side elevation as in FIGS. 4-6 where the nextcharge of product has been dropped into the next trailing length ofpackaging material, and the pull belts are driving the next trailinglength of packaging material downwardly using the stutter step method ofthe invention.

FIG. 7A shows a side elevation view of one of the pull belts of FIG. 7,engaging the packaging material against the forming tube and driving thepackaging material downwardly using the stutter step method of theinvention.

FIG. 8 is a flow chart illustrating an exemplary set of steps used inthe invention.

FIG. 8A is another flow chart, similar to that of FIG. 8, that may beused with the invention.

FIG. 9 shows a velocity/time profile using a three-step pull where thesustained maximum-velocity time periods are longer than the accelerationand deceleration time periods.

FIG. 10 shows a velocity/time profile where both the sustained maximumvelocity, and the number of stutter step pulls, are increased relativeto those of FIG. 9.

FIG. 11 shows a velocity/time profile where the maximum velocity timeperiod is essentially zero.

FIG. 12 shows a velocity/time profile where the velocity is reduced tosomething greater than zero during the intermediate reduced-velocityportions of the stutter steps and the frequency is modified.

FIG. 13 shows a velocity/time profile having multiple sustained maximumvelocities portions, separated by reduced velocity portions wherevelocity is at all times greater than zero and the frequency ismodified.

FIG. 14 shows another velocity/time profile where the maximum velocitytime period is essentially zero.

FIG. 14A shows a velocity/time profile similar to that of FIG. 14 butwhere there is variability in the shape of the velocity/time profile,and none of the individual stutter step jerks or pulls are identical toeach other.

FIG. 15 is a timeline showing a possible scenario involving theoperation of various functions of a packaging system over the course ofone bagging cycle that is part of a series or stream of such baggingcycles, for a single-pull bag system.

FIG. 16 is a simple block diagram of a programmable logic controller(PLC).

The invention is not limited in its application to the details ofconstruction, or to the arrangement of the components or methods setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various other ways. Also, it is to be understood that theterminology and phraseology employed herein is for purpose ofdescription and illustration and should not be regarded as limiting.Like reference numerals are used to indicate like components.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Turning now to FIG. 4, a packaging system 10 of the invention iscontrolled by a controller 12, typically a programmable logic computeror programmable logic controller (PLC). The primary activity of thesystem is implemented using a vertical form fill and seal (VFFS) machine14 which is illustrated herein, but is not necessarily limited to onlyVFFS machines. A first guide roll 16 is positioned between a packagingmaterial feed roll 18 and a pair of measure rolls 20 which form a nip 22therebetween. A second guide roll 24 is located downstream of nip 22. Aregistration sensor 26 is positioned between second guide roll 24 andnip 22. Downstream of second guide roll 24 is forming shoulder 28 whichis generally mounted above an elongate, downwardly-extending, formingtube 30 at the upwardly-disposed feed end 30A of the forming tube 30. Anelongate seal-forming platen 32 is mounted in an upright orientation,intermittently pressing against forming tube 30. First and second pullbelts 34 are mounted in upright orientations adjacent, and pressingagainst the forming tube 30, on opposing sides of platen 32 and drivenso as to advance downwardly against the forming tube. First and secondseal heads 36A, 36B, which may be rear and front seal headsrespectively, are mounted below the downwardly-disposed exit end 30B ofthe forming tube 30, in opposition to each other, and are spaced closelyoutside a downward projection of the forming tube 30. Take-away conveyor38 is located under forming tube 30 and under seal heads 36A, 36B. Thepackaging material feed roll 18 is mounted in a suitable location so asto provide a generally continuous length of rolled packaging material toVFFS machine 14. A product hopper 42 is positioned above and adjacentforming shoulder 28 so as to be able to drop product 44 into theunderlying forming tube 30. Each seal head 36A, 36B includes an upperheat seal jaw 46, a lower heat seal jaw 48, and a cutting element 50between the upper and lower seal jaws.

Packaging material 40 is selected, designed, and/or configured such thatany two facing surfaces of the packaging material can be heat sealed toeach other. Thus, overlapping opposing surfaces are sealed to each otherto form longitudinal seals, and facing elements of a given surface aresealed to each other to form transverse seals.

FIG. 4 shows the system at the stage where packaging material has beendrawn over first guide roll 16, through nip 22, past registration sensor26, past second guide roll 24, over forming shoulder 28, and ontoforming tube 30. Forming shoulder 28 and forming tube 30 havecollectively formed the previously flat sheet of packaging material intoa tubular orientation about forming tube 30, with longitudinal edgeportions of the packaging material oriented generally vertically andfacing each other, either as overlapping edge portions or as facingportions which can be formed into fin seals. Longitudinal seal platen 32has formed a plurality of lengths of such longitudinal seals, with thelengths of the seals overlapping each other, whereby each such seal is acontinuation of the next preceding longitudinal seal, thus to haveformed a longitudinally-sealed tube. A bottom transverse seal 52 hasbeen formed at the apparent leading edge of the longitudinally-sealedtube, thus to form a tubular package pre-form 53, sealed at the bottom,open at the top, and continuously longitudinally sealed from thetransverse seal to a height corresponding to the top of platen 32. Afirst charge of product 44 has been fed/dropped from hopper 42 into thepackage pre-form. A second charge of product 44 is seen in FIG. 4 in theprocess of being fed/dropped into hopper 42 as indicated by arrows 45.The pre-form has been advanced downwardly, using a jerky stutterstep-type drive motion of the invention, described in more detailfollowing. Seal heads 36A, 36B are withdrawn away from, but areadjacent, the sides of the package pre-form. Top 54 of product 44 in thepackage pre-form is below the bottoms 56 of the seal jaws, and below thebottom of transverse seal area 58, the transverse seal area beingillustrated by stippling in FIG. 4 between the seal jaws. The seal areadesirably, and typically, would be free from, namely devoid of, product44.

FIG. 5 shows the packaging system of FIG. 4 with heat seal heads 36A,36B closed on the tubular package pre-form at the seal area. In FIG. 5,the lower heat seal jaws 48 are forming a top transverse heat seal 60(see FIG. 6) across the top of the underlying length of the packagepre-form and above top 54 of the contained product, thus to finishclosing and sealing the package pre-form with the product containedtherein to make a closed and sealed package, containing the charge ofproduct 44. Simultaneously, cutting element 50 engages the packagingmaterial across the width of the package pre-form above top transverseheat seal 60, thus cutting away the underlying now-fully-sealed package62 from the overlying package pre-form 53. As also shown in FIG. 5,simultaneously with the lower heat seal jaws 48 forming the top heatseal on the underlying length of the package pre-form, upper heat sealjaws 46 are forming a bottom transverse heat seal 52 across the bottomof the next adjacent, and overlying, package unit length of packagingmaterial, thus forming the next succeeding package pre-form.

FIG. 6 shows the packaging system of FIGS. 4 and 5 with the seal headsagain withdrawn. As the seal heads withdrew from their sealing positionsshown in FIG. 5, package 62 was released from the grip of lower sealjaws 48. Having been cut away from the package pre-form by cuttingelement 50, package 62 fell by gravity onto take-away conveyor 38. Thus,package 62 is shown on take-away conveyor 38 in FIG. 6. Also shown inFIG. 6, overlying hopper 42 has been fully recharged with the nextcharge of product 44, ready to be dropped into the package pre-form, andplaten 32 has been advanced horizontally against the edges of the nextlength of packaging material, to form a continuation of the longitudinalseal in the longitudinally scaled tube.

FIG. 7 shows the next stage of the process, where the platen has beenwithdrawn from the packaging material at the forming tube as suggestedby arrows 55, and the next charge of product has been dropped fromhopper 42 into the underlying package pre-form.

A typical product which is dropped from hopper 42 is a collectiveproduct as described above, e.g., a dry food product. Examples of suchdry food products are various snack products such as chip products.Potato chips, corn chips, tortilla chips, pita chips and the like arerepresentative of such snack products. Another common product is drybreakfast cereals and other grain-related products. Still anotherproduct is popped popcorn. Such products have a number of productcharacteristics which make them susceptible to initially arriving in thebottom of the package pre-form in a relatively less dense condition, andwhich presents problems for the packager. Common characteristics mayinclude, without limitation, one, some, or all of:

-   -   The product is light weight.    -   The product is relatively fragile, easily broken.    -   The product is relatively dry.    -   The product has a coefficient of friction which impedes, but        does not stop, movement of the product elements relative to each        other.    -   Product configuration, from product element to product element,        is non-uniform such that the product exhibits different shapes.        For example, potato chips all have approximately the same        thickness, but different individual chips in a given package        have different lengths and widths, and the chips tend to        bend/curl during cooking, and the bend/curl configurations        differ from chip to chip. For example, many breakfast cereals        contain multiple different ingredients, each having a different        three-dimensional shape/configuration. For example, raisin bran        contains both flakes and dried raisins. Furthermore, as        described in more detail above in relation to popped popcorn,        product density—and therefore also the volume of a charge of        product—may change from one batch, or from one portion of a        batch, to another, which can (if the product is not adequately        mixed before measuring out each charge of product) result in        excessive head space for packages containing the higher density,        lower volume product charges.

Even where the product is not fragile, not light weight, notnon-uniform, the product can still arrive in the package pre-form in abulk density which is less than desired. Accordingly, increasing thebulk density of the product in the package, as well as improving theconsistency of the density, package to package, is desirable for thepackager.

As the product drops from hopper 42 into the package pre-form, therespective product elements lodge with respect to each other and withrespect to the side walls of the package pre-form in keeping with theirrespective physical properties. Especially the light weight, varyingconfigurations, and the friction properties affect the way the productelements come to rest relative to each other when first dropped into thepackage pre-form.

Still referring to FIG. 7, in the invention, when at least a portion ofthe charge of product has arrived in the package pre-form, controller 12may issue commands to measure rolls 20 and pull belts 34 to cause themeasure rolls and pull belts to begin simultaneously advancing thepackaging material, as indicated by downwardly-directed arrows 64. Inthe invention, such advance is a series of jerky downward stutter stepmovements of the package pre-form between respective advances andretractions of the platen in making longitudinal heat seals. Thepackaging material advance is a plurality of jerks, also referred toherein as stutter steps, between platen engagements when each advancerepresents a unit package.

Note by inspection of the figure that situations can occur at certaintimes in the machine cycle where a portion (e.g. an upper portion) of acharge of product may be present in the forming tube 30, even though theentire charge of product may also be simultaneously present in thepackage pre-form. This is because an upper portion of the packagepre-form is ordinarily wrapped around the forming tube 30. As productfirst begins to drop from the hopper 42 into the (empty) packagepre-form, it may initially fall through and then past (out of) theforming tube 30, coming to rest and beginning to accumulate at or nearthe bottom of the package pre-form just above the transverse bottom seal52. Immediately thereafter, subsequent falling product elements droponto the accumulating mass of product (inside the package pre-form) athigher and higher positions relative to the transverse bottom seal 52,until a portion of the product charge may be present in the forming tube30, and simultaneously present in the package pre-form, as shown. Stateddifferently, the package pre-form can, and often does (depending on thevolume of the product being packaged), extend into the forming tube 30,and this situation can exist while the charge of product is being dumpedinto the package pre-form.

The jerky stutter step advance is indicated in FIG. 7 by a first seriesof aligned and short, upwardly-directed arrows 62 spaced from each otheron the outwardly-disposed portion of pull belt 34, and a second seriesof aligned and downwardly-directed arrows 64 spaced from each otherunder transverse bottom seal 52 on the package pre-form. FIG. 7A showspull belt 34 in side elevation view, such that arrows 62 indicate anupward direction of advance on the outwardly-disposed portion of pullbelt 34 as in FIG. 7, and a downward direction of advance on theinwardly-disposed portion of the belt which presses the packagingmaterial against the forming tube. Of course, there is insufficient timeto perform any sealing operations on the package pre-form betweenindividual jerks in a series of jerks that form a given stutter stepadvance. Also, each individual jerk in the series typically moves thefilm by a distance which is small relative to the distance moved by aconventional film pull, e.g., by less than ⅓, or less than ⅕, or lessthan 1/10 of the bag length.

The stutter step advance may occur only during the period when theproduct is being dropped into the package pre-form, or only after theentire charge of product has been dropped into the package pre-form, orthe stutter step advance may occur both during and after the productdrop, e.g., the stutter step advance may begin during (or even before)the period when the product is being dropped into the package pre-form,and it may end after the entire charge of product has been dropped into(and is present in) the package pre-form.

Because the invention operates with a series of jerks, and intermediateperiods of lesser velocity, or no velocity, the acceleration required tomaintain desired throughput rates may, as a result, exceed thelimitations/capabilities of the system, in which case adjustments mayneed to be made to one or more of the system parameters. For example,the total time required to complete a pull may have to be increased.

Assuming, for example, a 250 mm pull in 833 ms in 5 individual pulls,using the equations shown above, the calculation is as follows:

Length per segment=250/5=50 mm.

Pull time per segment=83⅓/5=16.67 ms.  Velocity Calculation

VMAX can then be determined as follows:

Distance=(2×VMAX×T)/3.

With Distance=50 mm=0.3086 revolutions=308 counts and T=16.67 ms.

VMAX=(3×Distance)/(2× T)=924 counts/33.34 ms=27.71 counts/ms=27,710counts/sec.

Acceleration=VMAX/(T/3)=27710×3/16.67=4,986,803 counts/sec/sec.

Deceleration=−Acceleration=−4,986,803 counts/sec/sec.  Acceleration andDeceleration Calculations

The above calculations show that the acceleration and decelerationrequirements can become excessive and impose restrictions on the amountof film which can be pulled in the desired amount of time within theresponse limits of the system.

Certain steps can be taken to resolve the situation, for example andwithout limitation, one, some, or all of:

-   -   1) decrease the packaging material pull length per package unit        length;    -   2) increase the packaging material pull time per package unit        length in the machine cycle;    -   3) decrease the number of programmed jerk moves per package unit        length in the packaging material pull cycle;    -   4) decelerate to a speed greater than zero;    -   5) increase the energy input into the system; and    -   6) replace the power supply and other appropriate machine        elements with elements having greater energy input rate        capacities.

One example of a flow chart that can be used, for example in a PLC orother controller in any of the described packaging systems, toaccomplish the desired results of settling the collective product insidethe package pre-form by short stutter step pulls is shown as FIG. 8. Theflow chart of that figure is self-explanatory and requires no furtherexplanation in view of the foregoing detailed explanation of thedisclosed stutter step agitation method. Another flow chart, similar tothat of FIG. 8, is provided in FIG. 8A. The FIG. 8A flowchart is alsoself-explanatory, and it makes more explicit the fact that the number ofindividual stutter step pulls (NP) can be associated with any given filmpull. For example, if the packaging system is set up for double-pullbags, then the number NP of stutter step pulls (short pulls) may pertainto the first film pull, or to the second film pull, or both, for suchpackage. Still other methods can also be used, depending on thecapabilities afforded in the hardware being used to control the system.

As the measure rolls and pull belts engage the packaging material andaffect the stutter step/jerk motion of advancing the packaging material,a number of motion-related effects related to product settling, which werefer to as motion elements, can occur within the advancing packagepre-form.

A first motion element is the primary motion of the packaging material,which creates a first motion differential between the packaging materialand the contact product elements which are in contact with the packagingmaterial.

A second motion element is the motion which is thus imparted to thosecontact product elements whereby those contact product elements,themselves, move.

A third motion element is a second motion differential which is createdbetween the contact product elements and those non-contact productelements which are not in contact with the packaging material and whichare in contact with the contact product elements.

A fourth motion element is the motion of those so contacted non-contactproduct elements, which is imparted by the contact product elements.

A fifth motion element is the motion imparted to all the remainingnon-contact product elements as those product elements come into contactwith a product element which is already in motion.

From the foregoing description, the reader will appreciate that both theordinary film pull and the disclosed stutter step pulls typically movethe flexible packaging material in only one direction, namely, forward,or downward as represented in the orientation of FIGS. 4 through 7A.That is, at substantially all times during the course of a film pull orstutter step pull when the packaging material has a non-zero velocity,i.e. when such material is not momentarily at rest, the velocity of suchmaterial may be in the same direction, which we designate the forwarddirection. The magnitude of the velocity can increase and decrease, andthus acceleration of the packaging material can be bi-directional(forward and backward, or positive and negative), but the velocityitself is substantially uni-directional (including at some times zerovelocity) during the course of the machine packaging cycle.

Example System

A Hayssen® Ultima® VFFS machine is equipped with an Omron™ programmablelogic controller (PLC) as the control system, uniquely programmed tooperate according to the invention. The exemplary control system employsstepper motor technology to drive the measure rolls and pull belts. Theconfiguration is illustrated in FIGS. 4-7 and 7A. The control systemincludes a motion control system for control of the stepper motors. Themeasure rolls are assigned as the master axis and the pull belts are setup in a follower mode to run at speeds which match the surface speeds ofthe measure rolls, thereby accommodating the mechanical ratio betweenthe measure rolls and the pull belts. This ratio can be adjusted by theoperator as needed to compensate for e.g. packaging material slip due tohumidity, temperature, film characteristics, and other factors.

The pull belts follow the commanded position of the measure roll axis inan open loop configuration using stepper motors.

In the alternative, servo motors, or stepper motors with encodersattached for position feedback, can be used in a closed loopconfiguration with the measure roll axis designated as the master axis.

Another approach is to attach an encoder to the master axis and allowthe pull belt axis to follow the encoder rather than the commandedposition of the master axis. This forms a closed loop system which isvery much like the closed loop servo system.

Conventionally, a unit package is pulled in one or two, optionally threeor more, pulls depending on the length of the longitudinal back seal. Ifthe package length is longer than the platen seal bar, the pulltypically consists of two pulls, each of which approximates half of aunit package length. The longitudinal back seal is performed at the endof each pull when the packaging material is not moving, such that theends of the respective longitudinal seals overlap each other, thelengths of the overlapping seals depending on the lengths of thepackages being formed.

If the package length is equal to, or greater than, the length of thelongitudinal platen seal bar, the invention comprehends the use of twopulls, or more, with a stutter step motion coincident with at least oneof the pulls, to help the settling of product in the package pre-form.Restated, any time the package material is driven, with product in thepackage pre-form, the stutter step/jerk type drive is used unlessmultiple pulls are used, or the stutter function is disabled by theoperator, for a given package unit.

Thus, an answer to the settling problem is found by breaking thecontinuous normal pull into a series of shorter pulls or jerks betweenengagements of the longitudinal platen against the packaging material toform the longitudinal seals. In the series of short jerks, which seriesis referred to as a stutter step profile, each individual jerk in theseries moves the film by a distance which is small relative to thedistance moved by a conventional film pull, e.g., by less than ⅓, orless than ⅕, or less than 1/10 of the bag length.

For example, if it is desired to pull a 20 inch bag, rather than makinga single 20 inch pull, the invention makes a series of short, jerkypulls, for example 20 one-inch pulls, or ten two-inch pulls, or fivefour-inch pulls, or six 3.33-inch pulls, each pull coming to a completestop, or at least reducing pull speed, before starting the next pull.Since the machine controller, e.g. a programmable logic computer orprogrammable logic controller (PLC), is capable of dividing the pull byany number, using a variety of maximum velocities, a variety of minimumvelocities, a variety of acceleration rates, a variety of decelerationrates, the film pull can be divided into any number of segments,recognizing that the greater the number of pulls, potentially thegreater the total pull time, which may impact the total cycle time forforming, filling, and sealing the package.

The velocity of a given one of the pulls of the packaging material informing a given package in the prior art is, for example and withoutlimitation, commonly represented as a ⅓-⅓-⅓ profile. The first third ofthe pull starts at zero velocity and accelerates to the maximum velocity(VMAX). The second third of the pull is accomplished at the maximumcalculated velocity for that pull, and the third and final portion ofthe pull decelerates the packaging material pull from the maximumvelocity to zero velocity. This is the motion standard for the velocitycalculations required to produce a package of a desired length in theprior art. The same time and velocity principles apply in the invention.

As illustrated in prior art FIGS. 1-3, for any given packaging materialadvance, the area under the time/velocity graph represents the lineardistance of advance of the packaging material. Thus, for a givenspecified distance of advance, whatever the profile of the graph, thearea under the graph must be the same. So for a stutter step advancerather than a single pull as in FIG. 1, either maximum velocity can beincreased, or time can be increased, or acceleration and/or decelerationrates can be increased; or any combination of such elements can be used.Furthermore, the minimum velocity may in some cases be some valuegreater than zero for some or all of the stutter steps excluding, ofcourse, the final step. A full stop of the packaging material must beachieved at least once for each unit package in order for the platen andseal heads to be able to form the longitudinal and transverse seals.

The velocity/time profile for such an advance of the packaging materialusing a three step, jerky/stutter step, pull is illustrated in FIG. 9,where the sustained maximum-velocity time periods are longer than theacceleration and deceleration time periods. In FIG. 9, a series of threesubstantially similar stutter step pulls takes the place of aconventional film pull such as that of FIG. 1 (or such as either one ofthe film pulls in FIG. 3). The maximum velocity for the velocity profileof FIG. 9 is VMAX(9), and the overall jerky stutter step advance lastsfor a total pull time T. The pull time T in FIG. 9 may differ from thepull time T of FIG. 1 (and from the pull time T of FIG. 3), and themaximum velocity VMAX(9) may differ from the maximum velocity VMAX ofFIG. 1 (as well as VMAX of FIG. 3); however, VMAX(9) and T in FIG. 9 areselected such that the area under the curve of the FIG. 9 velocityprofile substantially equals the area under the curve of the velocityprofile of the film pull in FIG. 1 (or the area under the curve of thevelocity profile of either one of the film pulls in FIG. 3). Thiscondition ensures that the packaging material advances the same distanceover the course of the jerky stutter step advance—e.g., at least one baglength, or at least ⅓ or ½ of the bag length—as the distance traveled bythe packaging material over the course of the conventional film pull ofFIG. 1 (or either one of the film pulls in FIG. 3). Consequently, forexample, VMAX(9) of FIG. 9 may be selected to be greater than VMAX ofFIG. 1, or T in FIG. 9 may be selected to be greater than T of FIG. 1,or both.

FIG. 10 shows a velocity/time profile for a jerky stutter step advancesimilar to that of FIG. 9, but where the sustained maximum velocityVMAX(10) is increased relative to the sustained maximum velocity VMAX(9)of FIG. 9 over the same time period T, and the number of stutter stepshas been increased, which results in increased rates of acceleration anddeceleration relative to FIG. 9. In FIG. 9, a series of threesubstantially similar stutter step pulls takes the place of aconventional film pull such as that of FIG. 1 (or such as either one ofthe film pulls in FIG. 3). Just as in FIG. 9, VMAX(10) and T in FIG. 10are selected such that the area under the curve of the FIG. 10 velocityprofile substantially equals the area under the curve of the velocityprofile of the film pull in FIG. 1 (or the area under the curve of thevelocity profile of either one of the film pulls in FIG. 3). Thiscondition ensures that the packaging material advances the same distanceover the course of the jerky stutter step advance—e.g., at least one baglength, or at least ⅓ or of the bag length—as the distance traveled bythe packaging material over the course of the conventional film pull ofFIG. 1 (or either one of the film pulls in FIG. 3). Consequently, forexample, VMAX(10) of FIG. 10 may be selected to be greater than VMAX ofFIG. 1, or T in FIG. 10 may be selected to be greater than T of FIG. 1,or both.

FIG. 11 shows a velocity/time profile of still another jerky stutterstep advance, but where the maximum velocity time period is essentiallyzero, and where the maximum velocity is VMAX(11). In FIG. 11, a seriesof six substantially similar stutter step pulls takes the place of aconventional film pull such as that of FIG. 1 (or either film pull ofFIG. 3). Just as in FIGS. 9 and 10, VMAX(11) and T in FIG. 11 areselected such that the area under the curve of the FIG. 11 velocityprofile substantially equals the area under the curve of the velocityprofile of the film pull in FIG. 1 (or the area under the curve ofeither film pull of FIG. 3). This condition ensures that the packagingmaterial advances the same distance over the course of the jerky stutterstep advance—e.g., at least one bag length, or at least ⅓ or ½ of thebag length—as the distance traveled by the packaging material over thecourse of the conventional film pull of FIG. 1 (or either film pull ofFIG. 3). Consequently, for example, VMAX(11) of FIG. 11 may be selectedto be greater than VMAX of FIG. 1, or T in FIG. 11 may be selected to begreater than T of FIG. 1, or both.

FIG. 12 shows a velocity/time profile for still another jerky stutterstep advance that may be suitable for some sets of conditions. In thiscase, the profile exhibits a maximum velocity VMAX(12), and anintermediate minimum velocity VINT(12) greater than zero during theintermediate stutter steps/jerks, and the frequency is modified relativeto FIGS. 9-11, i.e., more individual stutter step pulls are included inthe series of FIG. 12. In FIG. 12, a series of eight stutter step pulls,the middle six of which are substantially similar to each other, takesthe place of a conventional film pull such as that of FIG. 1 (or eitherfilm pull of FIG. 3). The values of VMAX(12), VINT(12), and T in FIG. 12are selected such that the area under the curve of the FIG. 12 velocityprofile substantially equals the area under the curve of the velocityprofile of the film pull in FIG. 1 (or the area under the curve ofeither film pull of FIG. 3). This condition ensures that the packagingmaterial advances the same distance over the course of the jerky stutterstep advance—e.g., at least one bag length, or at least ⅓ or ½ of thebag length—as the distance traveled by the packaging material over thecourse of the conventional film pull of FIG. 1 (or either film pull ofFIG. 3). Consequently, for example, VMAX(12) of FIG. 12 may be selectedto be greater than VMAX of FIG. 1, or T in FIG. 12 may be selected to begreater than T of FIG. 1, or both.

FIG. 13 shows a velocity profile for another jerky stutter step advancethat may be suitable for some sets of conditions. This profile hasmultiple sustained maximum velocity portions, at a maximum velocityVMAX(13), separated by reduced velocity portions, at an intermediatevelocity VINT(13), where the velocity is at all times (between 0 and T)greater than zero, and the frequency is modified relative to FIGS. 9-12,i.e., a different number of individual stutter step pulls are includedin the series of FIG. 13. In FIG. 13, a series of seven stutter steppulls, the middle five of which are substantially similar to each other,takes the place of a conventional film pull such as that of FIG. 1 (oreither film pull of FIG. 3). Just as in FIG. 12, VMAX(13), VINT(13), andT in FIG. 13 are selected such that the area under the curve of the FIG.13 velocity profile substantially equals the area under the curve of thevelocity profile of the film pull in FIG. 1 (or the area under the curveof either film pull of FIG. 3). This condition ensures that thepackaging material advances the same distance over the course of thejerky stutter step advance—e.g., at least one bag length, or at least ⅓or ½ of the bag length—as the distance traveled by the packagingmaterial over the course of the conventional film pull of FIG. 1 (oreither film pull of FIG. 3). Consequently, for example, VMAX(13) of FIG.13 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 13may be selected to be greater than T of FIG. 1, or both.

In general, the profiles of FIGS. 9-13 show that a given length ofpackaging material can be advanced while using a wide variety of stutterstep profiles. The variety of the available profiles which can be usedwith the stutter step method is limited only by the mechanical limits ofthe machine drives and the imagination of the user in setting up theinstruction set in the software program which is entered into controller12. Such wide variety of profiles allows the user to adapt the stutterstep profile, and thus the stutter step pulls, to the particular productbeing packaged while ensuring a balance of

release of product from the seal area,

optimized product settling in the package,

use of limited package material length,

consistency of package results, and

acceptable quality control.

The calculations herein provide the key elements of the pull, themaximum velocity of each pull, and the minimum velocity of eachjerk/stutter step as well as acceleration and deceleration factors foreach pull. If no registration is required by printing on the packagingmaterial, such calculated profile will operate the system, dispensingthe desired package unit length each cycle. Where registration isrequired, registration sensor 26 senses a registration mark on thepackaging material and alerts controller 12, which adjusts the drives tothe measure rollers and/or the pull belts, thus to adjust the positionof the registration mark relative to the cut-off of the finished, closedand sealed package.

Where more than one pull of packaging material, and more than one platenengagement are used for a given package unit, at least one, but notnecessarily all, of the platen engagements, to form a longitudinal sealcomes after a stutter step advance. Namely, some of the pulls/advancescan be non-stutter step pulls/advances where multiple platen engagementsare used for a given package unit. Accordingly, the stutter step jerkyadvance is used after at least a portion of the charge of product hasbeen fed into the package pre-form, and may not be used during anadvance where no product has yet been fed into the package pre-form.

Thus, for example, for a two-step advance of the packaging material,where the packaging material is advanced two times and two longitudinalseals are made, for a given package unit, the first advance may takeplace immediately after at least a portion of a charge of productelements has been fed into the package pre-form. Given that the productis in the package pre-form, and an objective of the jerky stutter stepadvance is to settle the product and/or remove product from the sealarea, that first advance may follow a stutter step profile while thesecond advance may follow a profile more like that of FIG. 1. In thealternative, the first advance may be a conventional advance as in FIG.1 and the second advance may be a jerky stutter step advance. So long asat least one of the advances is a stutter step advance, the objectivesof product settling and/or product being freed from the seal area can bemet.

In any event, the settling provided by the invention can be achievedwithout any mechanical device touching any outside surface of thatportion of the packaging material which extends past the exit end of theforming tube, and without any physical touching of the packagingmaterial by a human operator.

In a further embodiment, not illustrated specifically in the drawings,the advance of the packaging material can start as a conventionalacceleration to maximum velocity as in FIG. 1, progress at constant VMAXvelocity for a portion of the VMAX time shown in FIG. 1, and proceed asa jerky stutter step portion of the VMAX time, subsequently deceleratingto zero velocity as in FIG. 1. Such embodiment thus envisions a velocityprofile as in FIG. 1, modified by a jerky stutter step velocity profileas shown in for example any of FIGS. 9-13, for a portion, but less thanall, of the time shown as VMAX in FIG. 1. Such modification can occur atany point along the time axis of FIG. 1, though typically, the jerkystutter step modification starts after velocity has reached VMAX.

Changing any pull parameter, such as pull length, pull degrees, machinespeed, acceleration rate, deceleration rate, minimum velocity, maximumvelocity, time at maximum velocity, time at minimum velocity, or printregistration, will cause the system to recalculate the remaining pullparameters.

As used herein, a “jerk” advance of the packaging material means eitherboth rapidly accelerating the packaging material and then deceleratingthe packaging material, or rapidly accelerating the packaging material,rapidly slowing the acceleration, and then again rapidly acceleratingthe packaging material.

In the alternative, a jerk can be a strong force rapidly applied to thepackaging material in the direction of advance of the packaging materialso as to rapidly apply acceleration tension to the film, such as a forcecalculated to reach a VMAX packaging material acceleration in ⅓ theanticipated pull time, but wherein the packaging material is preventedfrom advancing by a brake system. Such jerk force causes sufficient e.g.lateral flexing of the packaging material in the package pre-form tocause displacement of any product from the seal area and to at leastinitiate product element settling in the package pre-form.

At least first and second jerks are employed either before or after, orboth before and after, the formation of a given one of the longitudinalseals. Thus, where a jerk-type advance of packaging material is used, atleast two jerks are used to advance or otherwise tension the packagingmaterial after formation of a given longitudinal seal and beforeformation of the next longitudinal seal.

Additional Discussion

We now provide some additional discussion of aspects of the inventivetechniques and systems set forth in the detailed description above. Muchof this additional discussion simply emphasizes or otherwise repeatsinformation that is explicit or implicit (or both) in the foregoingdescription.

The settling techniques and systems described herein preferably employthe same mechanism that is used to advance or pull the packagingmaterial through the VFFS machine, but they control or drive thatmechanism in a rapid sequence of short, strong accelerations ordecelerations or both, to impart a jerking motion or agitation to thepackage pre-form and its contents, and thus promoting settling of theproduct in such pre-form. (Agitation of the package pre-form by othermeans, such as by the use of mechanical vibrating devices that contactthe bottom, side, or any outer surface or other surface of the packagepre-form can thus be eliminated, or, if desired, such other means ofagitation can be used in combination with the disclosed settlingtechniques and systems.) FIG. 14 shows a velocity profile, similar tothose of FIGS. 9-13, for a jerky stutter step advance that may besuitable for some sets of conditions. In this figure, the jerky stutterstep advance, which takes the place of a conventional film pull such asthat of FIG. 1, is a series of four substantially similar stutter steppulls, with a maximum velocity time period of essentially zero, and witha maximum velocity of VMAX(14).

The onset of the jerky stutter step advance occurs at a time that isdelayed relative to time=0. Furthermore, the time axis is labeled bothin terms of machine degrees, and in terms of milliseconds. The timevalues given in the figure—where the jerky stutter step advance beginsat 10 machine degrees or 55 msec, and ends at 50 machine degrees or 275msec—are realistic for the following specific but non-limitingconditions:

-   -   machine cycle rate=1.980 seconds/bag, which corresponds to        slightly more than 30 bags/min;    -   1 machine degree=5.5 msec; and    -   bag length=200 mm, where only one film pull (as modified by the        disclosed stutter step technique) is used.        The duration of the jerky stutter step advance is 40 machine        degrees or 220 msec, as indicated by the total pull time T        depicted in the figure. Given this value for T, and assuming        simple, uniform acceleration and deceleration for each of the        four substantially similar stutter step pulls, the value of        VMAX(14) can be calculated in order to ensure that the area        under the curve of the velocity profile equals the pull length,        which in this case is the bag length of 200 mm.

In one approach, we recognize that since the entire stutter step pull oradvance is made up of four individual, and substantially similar,stutter step pulls, each stutter step pull must advance the packagingmaterial by 200 mm/4=50 mm. Furthermore, each stutter step pull isrepresented by one triangular-shaped portion of the profile. Each suchtriangular-shaped portion can be reconfigured into a rectangle of equalarea, the rectangle having a height of VMAX(14) and a width of 5 machinedegrees (or 27.5 msec). The area of this rectangle is VMAX(14)*27.5msec, which must equal the 50 mm length calculated above. Solving forVMAX(14), we get a value of 50 mm/27.5 msec, or about 1.8 mm/msec.

We can also calculate the acceleration and decelaration associated withthe stutter step pulls, which acceleration and deceleration may forexample be supplied by one or more stutter step motors coupled to thepull belts in contact with the packaging material. If we assume eachtriangular shape of the velocity profile is symmetrical, with equalmagnitudes of acceleration and deceleration, we can then recognize thatthe velocity of the packaging material changes from 0 to VMAX(14), i.e.,from 0 to about 1.8 mm/msec in 27.5 msec, for an acceleration of about0.066 mm/msec² (and a deceleration of about—0.066 mm/msec²). Byappropriately applying these parameters to the control algorithm of thepackaging system, we can generate a pull velocity profile consisting offour 50 mm stutter step pulls in 40 machine degrees, or 220milliseconds, substantially as shown in FIG. 14.

In some cases it is desirable or necessary to introduce variability intothe stutter step advance. An example of such variability is shown inFIG. 14A. The velocity/time profile of the packaging material in thisfigure is similar to that of FIG. 14, but where variability is added,such that none of the individual stutter step jerks or pulls areidentical to each other. The individual stutter step pulls may differfrom each other in terms of maximum velocity, minimum velocity, maximumvelocity time period (i.e., the dwell time (if any) at the maximumvelocity), minimum velocity time period (i.e., the dwell time (if any)at the minimum velocity or at an intermediate velocity), time orduration of the individual stutter step pulls, and furthermore, theacceleration and deceleration (changes in velocity with time) need notbe constant or smooth for any of the individual stutter step pulls. FIG.14A illustrates several ways in which individual stutter step jerks in aseries of jerks can differ: the first and second stutter step jerks haveshorter durations than the third and fourth stutter step jerks; themaximum velocity of the first stutter step jerk is greater than that ofthe second and fourth jerks, and even greater than that of the thirdjerk; and the maximum velocity time period of the first, second, andfourth stutter step jerks is substantially zero, whereas that of thethird jerk is nonzero and substantial. The jerk-to-jerk variability maybe programmed into the operation of the packaging machine and system.However, even with such variability, the area under the velocity/timeprofile is still equal to the distance advanced by the packagingmaterial over the course of the jerky stutter step advance, e.g., atleast one bag length, or at least ⅓ or ½ of the bag length.

Of course, it is also possible, and simplest, to configure the packagingsystem so that the individual stutter step pulls, in a series of suchpulls that form a stutter step advance, are substantially identical toeach other, as shown in FIGS. 9, 10, 11, and 14. In cases where theminimum velocity for stutter step pulls between the first and last suchpull is non-zero, such as in FIGS. 12 and 13, then the intermediatestutter step pulls (i.e., all such pulls except for the first and thelast) may all be substantially identical to each other, and may havesubstantially the same maximum velocity, and the same acceleration anddeceleration, as the first and last such pulls.

In order to make the most efficient and effective use of the timeallocated to the stutter step advance, it is desirable to maximize thenumber of jerks over the course of the pull. This can be done by using avelocity/time profile whose maximum velocity time period (the dwell timeat the maximum velocity) is zero or substantially zero (see e.g. FIGS.11, 12, and 14), and whose intermediate minimum velocity (the relativeminima in the velocity profile not including the beginning and end ofthe stutter step advance) is non-zero (see e.g. FIGS. 12 and 13). Of allthe velocity/time profiles shown in the figures, the profile of FIG. 12best illustrates the combination of these two features in one profile.

To maximize the productivity of the packaging machine—and minimize thecycle time required to process one bag or package of product—it is alsodesirable to begin or initiate the stutter step advance as early in themachine cycle as possible, e.g., while product is being loaded ordropped into the open-ended package pre-form, and before the entirecharge of product is contained in such pre-form. In such cases,depending upon factors such as the type of product being loaded, thespeed with which the product is dropped into the package pre-form, thesize of the charge of product, the bag length, the total pull time T ofthe stutter step advance, and so forth, the stutter step advance may befinished by the time product loading is complete (and the entire chargeof the product is contained in the pre-form), while in other cases thestutter step advance may not be finished but may continue or extendbeyond such time as the product loading is complete.

In this regard, the relationship between the time when the stutter stepadvance (agitation to promote product settling in the package pre-form)is occurring and when product loading and other machine or systemprocesses are occurring in the context of one complete machine cycle isbest illustrated in FIG. 15. FIG. 15 is a timeline showing a possiblescenario involving the operation of various functions of a packagingsystem over the course of one entire bagging cycle, for a single-pullbag system. The timeline illustrates the general operation of selectedfunctions of a VFFS machine that employs the stutter step settlingtechnique as disclosed above. The various functions are depicted assimple line segments on a timeline to help the reader better understandrelationships that may exist between the onset, duration, or terminationof one function and the onset, duration, or termination of otherfunctions of the machine.

The timeline of FIG. 15 is labeled both in terms of machine degrees, forease of programming, and in terms of milliseconds. The timeline depictsone cycle of operation of a VFFS machine, starting at 0 degrees (and 0msec) and ending at 359 degrees (and 1000 msec). The value of 1000 msecassumes a machine throughput of 60 bags/minute, or 1 bag per second. Ifthe machine throughput was reduced to 30 bags/minute, the endpoint ofthe timeline would change to 2000 msec, but the endpoint in machinedegrees would remain the same, i.e., 359 degrees. The throughput of themachine can of course be selected as desired, within permissible limitsof fill speed, film tension, seal formation time, and so forth, and isusually selected as the fastest speed and greatest throughput possiblewhile still maintaining an acceptably high sealed package quality andsufficiently low reject rate. For reasons that will become more apparentbelow, the single machine cycle at issue is shown in the context of animmediately preceding machine cycle, and an immediately followingmachine cycle, which the reader will understand to represent only a fewin a long series of machine cycles.

The functions shown in FIG. 15 are intended to be neither exhaustive norlimiting, but merely representative of selective aspects of one possiblemachine embodiment. Thus, additional machine functions not shown in FIG.15 can be performed, and one or some of the machine functions includedin the figure may be omitted, in some cases. The reader will alsounderstand that the various functions depicted in the single machinecycle at issue in FIG. 15 can, if desired, be replicated in theimmediately preceding machine cycle, and in the immediately followingmachine cycle, and indeed in all the machine cycles in the series, ifthe same type of package is being produced by each such machine cycle.

In FIG. 15, segment 1502 represents a film advance, beginning at time t1and ending at time t2. Segment 1504 represents agitation of the film(packaging material) and as much of the product as is contained in thepackage pre-form, to promote product settling. Segment 1504 begins attime t3 and ends at time t4. A series of short arrows 1503, drawn closeto the segment 1502, represents the series of jerky stutter step pullsthat create the agitation of segment 1504, such stutter step pullscollectively making up at least part of the film pull of segment 1502.Segment 1506, beginning at time t5 and ending at time t6, represents theperiod during which the charge of product in the hopper is released andallowed to fall through the hopper opening into the package pre-form. Insome cases discussed further below, this hopper dump period can extendinto the immediately preceding machine cycle, as indicated by theextension 1506′ to the segment 1506, where the extended segment 1506′begins at time t5′ and ends at time t6, or at any time between t5′ andt6 as appropriate depending on the product drop time. Segment 1508,beginning at time t7 and ending at time t5, represents the period duringwhich the (now closed) hopper is filled with a new charge of product.Segment 1510 represents the period during which the heated platenpresses against overlapping edges of the flexible packaging material toform the longitudinal seal of the packaging tube pre-form. Segment 1510begins at time t9 and ends at time t10. Segment 1512 represents theperiod during which transverse seals are formed by closing the heat sealjaws such as those depicted schematically in FIG. 5. In particular, alower heat seal jaw forms a top (transverse) seal in the package thathas just been filled and agitated, and an upper heat seal jaw forms abottom (transverse) seal in the (currently empty) packaging tubepre-form upstream of the current package. Segment 1512 begins at timet11 and ends at time t12. Finally, segment 1514 represents the periodduring which a knife or other cutting device cuts transversely throughthe packaging material to separate the now-filled and sealed currentpackage from the next package pre-form to be filled. Segment 1514 beginsat time t13 and ends at time t14.

The start and end times of the various line segments in the figure areshown to be separated from each other for generality and for purposes ofillustration so that the various times can be given the unique labelst1, t2, t3, etc. However, the reader will understand that some of thelabeled times can be the same or substantially the same. For example, t1can equal t3, and t2 can equal t4, such that the film pull function(segment 1502) and the agitation function (segment 1504) occur at thesame time periods. The time difference t4−t3 equals the total pull timeT of the stutter step advance as discussed above.

Of particular significance is the relationship between the agitationfunction and the hopper dump (or product fill) function. In the priorart, where a bottom shaker plate was used to agitate and settle thecontents of the packaging tube pre-form, agitation did not begin untilthe full charge of product was contained in the open-ended packagepre-form. (Furthermore, the localized nature of the agitation at thebottom of the bag tended to result in product damage or breakage.)However, in the disclosed technique, at least some of the agitation canoccur while the product is still being loaded into the packaging tubepre-form (e.g., while some product elements are still being dropped intothe pre-form), and as the pre-form is being lowered by operation of thefilm advance function towards the take-away conveyor 38 as seen in FIGS.4-7. By operating the system in this fashion, with overlap between theagitation function and the hopper dump (or product fill) function, thetime required for each bagging cycle can be reduced, and theproductivity of the machine system (e.g. in bags/minute) can becorrespondingly increased.

Thus, if we refer to the time during which the agitation occurs as anagitation period (such as segment 1504), and the time during whichproduct loading occurs as a loading period (such as segment 1506), thenthe agitation period preferably overlaps the loading period. That is, atleast some of the agitation preferably occurs while the open-endedpackage pre-form is being filled, or before the last product element ofthe charge of product is contained in the package pre-form. In somecases, the agitation period and loading period may satisfy one or bothof the following relationships: the agitation period overlaps at leasthalf of the loading period; and the loading period overlaps at leasthalf of the agitation period (e.g. overlaps at least half of the totalnumber of jerky stutter step pulls, assuming such jerky pulls are ofsubstantially equal duration).

Despite the preference for an overlapping agitation and loading period,in some circumstances—depending on details of the collective product,flexible packaging material, package dimensions, and features andlimitations of the VFFS machine—it may be neither practical nordesirable to have such an overlap. Furthermore, the relationship of theagitation period (such as segment 1504) to the loading period (such assegment 1506), and to other functions represented by segments in FIG.15, may be very different from the relationships depicted in thatfigure.

For example, there are many situations when running a VFFS machine inwhich it is highly desirable to begin the product loading (hopper dump)while the heat seal jaws are closed to form the bottom transverse sealof the package pre-form, or even to begin such loading slightly beforethe heat seal jaws close (in view of the short time delay between themoment when the first product elements begin falling from the hopper andthe moment those product elements reach the bottom of the packagepre-form). In this way, we can avoid transferring to the newly formed,virgin transverse bottom seal the full force of the product beingdropped, and can instead cushion at least some of that force by the heatseal jaws, the closed heat seal jaws also serving to shield the virginbottom seal from the full brunt of such force and prevent a failure ofsuch seal. This can be of particular concern when the flexile packagingmaterial is or comprises a polyethylene film, since a seal formed by twopolyethylene film portions can be quite weak at the moment the heat sealjaws open due to the gelatinous, molten condition of the seal, beforethe heated seal region is allowed to thoroughly or even partially cooland harden.

Consequently, the loading period (see segment 1506) can be shiftedrelative to its position shown in FIG. 15. As indicated in FIG. 15 bythe extended segment 1506′, the starting point t5 (the beginning ofproduct loading/hopper dump for the depicted machine cycle) can occureven before t=0, that is, it can occur during the immediately precedingmachine cycle, at any time after the jaws close in such preceding cycle(or coincident with the jaws closing or even slightly before, takinginto consideration the elapsed time for product to drop from the hopperto the package pre-form), at a time that is analogous to the time t11 inthe depicted machine cycle but that occurs before t=0. The ending pointt6 of the product loading period can then occur at any time after t5,dependent on factors such as the type of product, the drop distance fromthe hopper to the package pre-form, the machine speed, and so forth. Inthis regard, the ending point t6 of the product loading period may alsooccur in the preceding machine cycle (before t=0 in FIG. 15), whereuponthere is no overlap of the loading period with the agitation period, orthe point t6 may occur between time t3 and t4, whereupon there isoverlap of those two periods. The reader should also note that to theextent t6 is interpreted to represent the moment when the hopper gatecloses, then the actual time when product loading is complete—that is,when the last product element from the product charge reaches the end ofits travel and actually falls onto the mass of other product elementsthat have collected in the partially formed package pre-form—may occurafter t6.

Of the many possible situations the machine designer may encounter usingthe disclosed agitation techniques and machine cycles, we note thefollowing three:

-   -   (1) the starting point t5 (the beginning of product loading        period for the bag that becomes fully sealed in the depicted        machine cycle) can occur during the machine cycle at issue,        i.e., after t=0, as depicted in FIG. 15, and the ending point t6        can occur during or after (as shown in FIG. 15) the agitation        period, such that the product loading period and the agitation        period substantially overlap with each other; or    -   (2) the starting point t5 can occur before the machine cycle at        issue, i.e., during the preceding machine cycle and before t=0,        while the ending point t6 occurs during the agitation period        (segment 1504) of the machine cycle at issue, e.g., after t3 and        on or before t4, such that the product loading period and the        agitation period again overlap with each other; or    -   (3) both the starting point t5 and the ending point t6 can occur        before the machine cycle at issue, i.e., during the preceding        machine cycle and before t=0, or t6 may alternatively extend        into the current machine cycle and occur after t=0 but before        t3, whereupon in either case there will be no overlap of the        product loading period with the agitation period, and the entire        charge of product would be present in the package pre-form        before the start of the agitation.

The reader should therefore be careful in interpreting the machine cycledepicted in FIG. 15. As explained above, the loading period during whichthe product charge is dropped from the hopper into the open-endedpackage that is agitated during the depicted segment 1504 and thatbecomes fully sealed (top-sealed) during the depicted segment 1512 mayactually start (and in some cases end) in the immediately precedingmachine cycle, before t=0. In such cases, another product charge(loading period) would typically occur during the machine cycle depictedin FIG. 15, but that charge would be for a subsequent packageimmediately upstream of the package that becomes fully scaled in themachine cycle at issue (such subsequent package being agitated and fullysealed in the “immediately following machine cycle” of FIG. 15). Manydifferent configurations of programming the termination cycle of themachine can be used to ensure the cycle is stopped after clearing thelast filled bag from the partially formed tube without producing anempty bag on the first machine cycle.

The reader will note that the single VFFS cycle of operation of FIG. 15comprises two main sections, namely, a film pull section, during whichthe flexible packaging material is being pulled and advanced, and asealing section, during which the flexible packaging material is beingsealed by the platen, the seal jaws, or both, and hence the film isstopped relative to the forming tube.

The functions shown in FIG. 15, as well as other functions not depictedin the figure but discussed elsewhere herein, are preferably governed byan electronic controller such as a PLC. A simple block diagram of a PLCis provided in FIG. 16. The PLC typically includes a microprocessor orother processor, memory, and input and output interfaces as shown. ThePLC also typically includes a power supply that powers the processor andthe interfaces. A communications interface couples to the processor, andallows for programming of the processor by an external programmingdevice. The processor couples directly or indirectly to one or moreinput devices through the input interface, and it couples directly orindirectly to one or more output devices through the output interface.The actions or functions carried out by the packaging machine or system,such as those shown in FIG. 15, can be programmed into the PLC andstored in its memory.

Examples of output devices the PLC may couple to include: a pull belt(or pair of pull belts) to accomplish the film advance and stutter stepagitation; actuator(s) to move the pull belt(s) into and out of contactwith the packaging material; a measure roll; a hopper device or devicesto accomplish dumping one load or charge of the collective product fromthe hopper into the tubular construct by opening the hopper, as well asfilling another load of the product into the hopper; a heated platenseal bar to accomplish longitudinal sealing of the tubular construct,and associated actuator(s); transverse seal jaws to accomplishtransverse or end sealing of the tubular construct; and a knife, heatedwire, or other known device to cut through the flexible packagingmaterial between transverse seals, so that individual bags or packagescan be produced from the continuous roll of packaging material. Examplesof input devices the PLC may couple to include one or more: filmregistration sensors; temperature sensors; weight sensors; jaw closedindicators; low film indicators; pushbuttons; selector switches;operator touch screens; program entry devices; and the like.

Although the invention has been described with respect to variousembodiments, this invention is also capable of a wide variety of furtherand other embodiments within the spirit and scope of the appendedclaims.

Those skilled in the art will now see that certain modifications can bemade to the apparatus and methods herein disclosed with respect to theillustrated embodiments, without departing from the spirit of theinstant invention. And while the invention has been described above withrespect to the preferred embodiments, it will be understood that, inlight of the disclosure here, the invention can be adapted to numerousrearrangements, modifications, and alterations, and all sucharrangements, modifications, and alterations are intended to be withinthe scope of the appended claims.

To the extent the following claims use means plus function language, itis not meant to include there, or in the instant specification, anythingnot structurally equivalent to what is shown in the embodimentsdisclosed in the specification.

1. A method of making a sealed package containing a charge of compoundproduct, the method comprising: forming a tubular package pre-form bysteps that include wrapping flexible packaging material around a formingtube, sealing edge portions of the packaging material together to form alongitudinal seal, and sealing other portions of the packaging materialtogether to form a first transverse end seal; advancing the flexiblepackaging material along and past the forming tube using a pullingapparatus adapted to engage and pull the flexible packaging material;loading the charge of compound product into the tubular package pre-formthrough the forming tube; and agitating the tubular package pre-formusing the pulling apparatus.
 2. The method of claim 1, wherein theagitating comprises advancing the flexible packaging material in aseries of jerks using the pulling apparatus.
 3. The method of claim 1,wherein the pulling apparatus advances the flexible packaging materialin a uni-directional manner.
 4. The method of claim 1, wherein thepulling apparatus comprises a pull belt.
 5. The method of claim 1,wherein the agitating begins before the loading ends.
 6. The method ofclaim 1, wherein the agitating is carried out over an agitation periodand the loading is carried out over a loading period, and wherein theagitation period at least partially overlaps the loading period.
 7. Themethod of claim 6, wherein the agitation period substantially completelyoverlaps the loading period.
 8. The method of claim 1, wherein theagitating is carried out over an agitation period and the loading iscarried out over a loading period, and wherein the agitation period doesnot overlap the loading period.
 9. A sealed package containing a chargeof compound product, made using the method of claim
 1. 10. A method ofmaking a sealed package containing a charge of compound product, themethod comprising: forming a tubular package pre-form by steps thatinclude wrapping flexible packaging material around a forming tube,sealing edge portions of the packaging material together to form alongitudinal seal, and sealing other portions of the packaging materialtogether to form a first transverse end seal; advancing the flexiblepackaging material along and past the forming tube using a pullingapparatus adapted to engage and pull the flexible packaging material;and loading the charge of compound product into the tubular packagepre-form through the forming tube; wherein the advancing comprisesagitating the tubular package pre-form using the pulling apparatus, theagitating adapted to settle the compound product in the tubular packagepre-form.
 11. The method of claim 10, wherein the agitating comprisesadvancing the flexible packaging material in a series of jerks using thepulling apparatus.
 12. The method of claim 10, wherein the pullingapparatus advances the flexible packaging material in a uni-directionalmanner.
 13. The method of claim 10, wherein the pulling apparatuscomprises a pull belt.
 14. The method of claim 10, wherein the agitatingbegins before the loading ends.
 15. The method of claim 10, wherein theagitating is carried out over an agitation period and the loading iscarried out over a loading period, and wherein the agitation period atleast partially overlaps the loading period.
 16. The method of claim 15,wherein the agitation period substantially completely overlaps theloading period.
 17. The method of claim 10, wherein the agitating iscarried out over an agitation period and the loading is carried out overa loading period, and wherein the agitation period does not overlap theloading period.
 18. A sealed package containing a charge of compoundproduct, made using the method of claim
 10. 19. A vertical form fill andseal (VFFS) machine, comprising: an unwind station for receiving a rollof flexible packaging material; a forming tube around which the flexiblepackaging material can be wrapped; a pulling apparatus adapted to engageand pull the flexible packaging material along and past the formingtube; one or more seal stations, disposed proximate the forming tube, atwhich edge portions of the flexible packaging material are sealedtogether to form longitudinal seals, and other portions of the flexiblepackaging material are sealed together to form transverse end seals,thereby to form a series of tubular package pre-forms from the flexiblepackaging material; a drop station from which a charge of compoundproduct can be dropped into a given one of the tubular package pre-formsthrough the forming tube; and a controller coupled to at least thepulling apparatus, the one or more seal stations, and the drop station;wherein the controller is configured to agitate the tubular packagepre-form using the pulling apparatus to promote settling of the compoundproduct in the given tubular package pre-form.
 20. The machine of claim19, wherein the pulling apparatus comprises a pull belt, and wherein thecontroller is configured to agitate the tubular package pre-form byoperating the pull belt according to a series of short jerks.